I. Technical Field
The present invention relates to a plasma display device and a method of manufacturing a phosphor material constituting a phosphor layer thereof.
II. Description of Related Art
A plasma display device (below, written as “a PDP device”) has attracted attention as an image display device capable of realizing high definition and a large screen in recent years.
A plasma display panel (below, written as “PDP”) is a part where the images of the PDP device are displayed, and is configured with a front substrate and a rear substrate. The front substrate is configured with display electrodes consisting of a striped transparent electrode and a metal bus electrode formed on a glass substrate, a dielectric layer covering the display electrodes, and a protective layer. On the other hand, the rear substrate is configured with a striped address electrode formed on the glass substrate, a ground dielectric layer covering the address electrode, barrier ribs formed on the ground dielectric layer, and a phosphor layer formed between each barrier rib.
The front substrate and the rear substrate are sealed by a sealing material formed around their circumference. Then, a discharge gas consisting of neon, xenon, etc. is sealed into a space between the front substrate and the rear substrate created by the sealing.
A PDP with such a configuration performs image display by discharging the discharge gas through a voltage applied to a group of electrodes consisting of the display electrode, a sustain electrode, and a scan electrode, to thus excite the phosphor layers in response to ultraviolet rays generated by discharge.
The PDP performs a full-color display by performing additive color mixture of so-called three primary colors (red, green, and blue). In order to perform this full-color display, the PDP is equipped with phosphor layers that emit in red, green, and blue. The phosphor layer of each color is configured by layering the phosphor material of each color.
A surface of Zn2SiO4:Mn, which is one of typical green phosphor materials, is charged negatively. Therefore, positive ions of neon and xenon generated in the discharged gas upon the PDP displaying easily cause an ion collision to the negatively charged Zn2SiO4:Mn. The surface of Zn2SiO4:Mn deteriorates by this collision. Therefore, when the PDP device is used for a long time, green luminance decreases due to the deterioration of the Zn2SiO4:Mn.
In order to solve this problem, Unexamined Japanese Patent Publication No. H11-86735, for example, discloses layering a film that can make a positive polarity on the surface of Zn2SiO4:Mn with a vapor deposition method and a firing method.
However, because the surface of Zn2SiO4:Mn is coated with a film substance that does not emit in layering films with the vapor deposition method and the firing method, there is a problem that the luminance of Zn2SiO4:Mn decreases.
Further, a PDP is proposed in which phosphor particles for PDP coated with a coating film of metal oxide by attaching metal alkoxide on the surface of the phosphor material such as Zn2SiO4:Mn and firing this are used (for example, refer to Unexamined Japanese Patent Publication No. H10-195428).
However, because the metal alkoxide is a compound containing organic substances, a carbon-based compound remains on the phosphor surface if the firing is not performed sufficiently. This carbon-based compound decomposes by discharge. In particular, the carbon-based compound decomposed with long hours of use is released in the discharge space, and the discharge becomes unstable.